[Rob the rake]

As a committed organic gardener the use of persistent chemical poisons is anathema to me. I've discovered a few good alternatives, via the wonders of the World Wide Web, but I'm interested to know what works for others, particularly since it would be useful to discourage the ants which have begun to populate the garden since the rise in global warming. Note that I say discourage - I have no intention of obliterating these insects and indeed feel uncomfortable with killing anything unless absolutely necessary. Some recipes I've used seem to gum up the leaves of plants, affecting their growth, and I'd like to avoid these

For insects other than ants, aphids in particular, this recipe works well for me:

1 and 1/2 tsp Castile soap
1 and 1/2 tsp white vinegar
Made up to a gallon and applied via spray bottle, sparingly applied in the evenings to avoid direct sunlight.

For an extremely effective and non-toxic weedkiller, used last year by my allotment neighbour, and one I'm just about to trial myself for paths and hard-to-weed crevices.

1/2 a cup of Ecover washing up liquid, or similar.
2 cups Epsom salts
Made up to a gallon in white vinegar

The recipe doesn't say whether the ingredients should be added together or one at a time, so my intention is to dissolve each ingredient in half of the vinegar then blend the two. When Emma used it, it seemed to effortlessly knock down anything it touched, so care will be needed. I'll report back after using it. She hasn't been around for a while, so I've been unable to ask her how she made it up.

There are several other insecticides mentioned in the linked articles shown below; the tomato leaf one seems particularly interesting.

https://www.treehugger.com/natural-homemade-insecticides-save-your-garden-without-killing-earth-4858819

https://verminkill.com/homemade-aphid-killers/#:~:text=A%20combination%20of%20vinegar%20and%20Castile%20soap%20is,main%20ingredients%20being%20mineral%20oil%20and%20olive%20oil.

[Clactonite]

Rob, I also have used the soap spray to great effect with greenfly and blackfly.  I was moved to this as my grandad did this fifty years ago (and I am turning into him it appears) after buying some expensive organic pesticide that allowed harvesting within two days.  This was probably true.  It was totally ineffective, so why question that claim.

I just shaved some old left-over bar soap with a potato peeler and shoved this into a 1 litre bottle.  I filled the bottle with warm water (to aid dissolving no more) but left a gap at the top to allow shaking.  After a few days this makes a gloopy substance.  I then transfer a small amount of goo from this "feeder" bottle to my sprayer and go at the beasts.  I've read on this site that some folk just add washing-up liquid to their spray bottle and that is easily effective.  The results are staggeringly effective.

[Rob the rake]

  I've read on this site that some folk just add washing-up liquid to their spray bottle and that is easily effective.

Thanks for your comments. What kind of soap is it, out of interest?
I tried the mild green washing up liquid from the adverts, but found that it left a gummy residue which damaged and discoloured the leaves of some plants; most notably chillies and sweet peppers. The organic Castile soap used in my posted recipe is benign in that respect.

[Clactonite]

I used "Simple" it's for sensitive skin... and plants apparently.   
I guess any so-called "pure", "simple" or "sensitive" soap would do as it should have less additives.

[rowlandwells]

I have gone with some organic sprays and insecticides but I have to say and make no bones about it I'm not a committed  organic gardener I still use some chemicals for weed control that are more effective on certain weeds but I am mindful of the need to protect wildlife but used sensibly chemicals can still be used well using it  doesn't   seem to have effected the wild life round our allotments there of plenty